The use of aminopolycarboxylates generally as laundry detergent additives is disclosed in the art. For example, the prior art describes laundry detergent compositions which include nitrilotriacetates (NTA), ethylenediaminetetracetates (EDTA), diethylenetriaminepentaacetates (DTPA), and hydroxyethylethylenediaminetriacetates (HEDTA).
U.S. Pat. No. 4,560,491, Curry and Edwards, issued Dec. 24, 1985, discloses laundry detergent compositions, essentially free of phosphate detergency builders, containing an aluminosilicate or organic detergency builder and from about 0.5% to 10% by weight of the chelant, HEDTA. The list of suitable organic detergency builders disclosed includes aminopolycarboxylates, such as NTA, EDTA and DTPA. Examples I and II disclose liquid detergent compositions containing DTPA and HEDTA. Example III discloses a granular detergent composition containing NTA and HEDTA.
U.S. Pat. No. 4,397,776, Ward, issued Aug. 9, 1983, discloses liquid laundry detergent compositions, having a pH between 9 and 13, containing alpha-amine oxide surfactants and from about 0.01% to about 25% by weight of a heavy-metal chelating agent. The chelating agent sequesters heavy-metal ions and thus enhances the stability of the alpha-amine oxides. The preferred chelating agents include aminopolycarboxylates, such as NTA, EDTA, DTPA, and HEDTA.
U.S. Pat. No. 3,920,564, Grecsek, issued Nov. 18, 1975, discloses softener/detergent formulations containing surfactants, quaternary ammonium or diamine fabric softeners, and a builder salt selected from aminopolycarboxylates and/or sodium citrate. Examples of suitable aminopolycarboxylates include NTA, EDTA and HEDTA.
U.S. Pat. No. 3,151,084, Schiltz et al, issued Sept. 29, 1964, discloses alkylbenzenesulfonate-containing detergent compositions in which solubility is said to be improved by the addition of 0.25%-4% of a mixture of EDTA and a solubilizing agent selected from salts of N,N-di(2-hydroxyethyl) glycine, iminodiacetic acid, NTA and HEDTA.
None of these references disclose detergent compositions, substantially free of peroxygen bleaches, which contain TTHA.
Moreover, the aminopolycarboxylates disclosed in those patents are not as effective as TTHA in terms of the removal of organic stains from fabric.
The art also discloses detergent compositions which may include TTHA as a peroxygen bleach stabilizer. For example, British Pat. No. Specification 866,492, Aiken and Howard, published Apr.26, 1961, discloses detergent compositions containing surface active agents, peroxygen bleaching compounds and, as a stabilizer for the bleach, a chelating agent of the general formula: ##STR1## The specification states that either DTPA or TTHA may be used to stabilize the peroxygen bleach.
British Pat. Specification No. 1,383,741, Howard, published Feb. 12, 1975, discloses the use of aminopolycarboxylate chelating agents as stabilizers for peroxygen bleach compounds used in detergent compositions and textile bleaching processes. The preferred chelating agent disclosed is 1,3-diamino-propane-2-ol-N,N,N',N'-tetraacetic acid. The compositions may additionally include water-soluble salts of a compound having the following formula: ##STR2## where n is a positive integer. The examples disclose peroxy bleach-containing detergent compositions which include DPTA.
British Pat. Specification No. 917,495, Chesner, published Feb. 6, 1963, discloses a bleaching solution containing peracetic acid and an aminopolycarboxylic acid of the general formula: ##STR3## where n is at least one. The aminopolycarboxylate acts to stabilize the peracetic acid during bleaching.
None of these references disclose the compositions of the present invention or recognize the unique fabric stain removal properties of TTHA in the context of laundry detergent compositions, substantially free of peroxygen bleach.